Method and apparatus for implementing matched filters in a wireless communication system
The present invention discloses a method and apparatus for implementing matched filter in a system using QPSK modulation. In the present invention, a multiplier is changed as a multiplexer by using the characteristic of the pilot sequence (or training sequence) so as to implement the matched filter.
1. A method for implementing matched filters in a wireless communication system, comprising:
oversampling and extracting a pre-processed received signal so as to obtain the in phase components and the quadrature components of respective sample points in a plurality of sampling sequences;
converting and combining the in phase components and the quadrature components of respective sample points in the same sampling sequence for the respective sampling sequence according to a pre-defined selection signal so as to obtain a plurality of corresponding matched filtered results; and
buffering and comparing the plurality of matched filtered results, so as to determine an optimum matched sampling sequence, the matched filtered result to which the optimum matched sampling sequence corresponds has the greatest value.
2. The method according to claim 1 , wherein the pre-defined selection signal is based on a known training sequence.
3. The method according to claim 2 , wherein the length of each sampling sequence is equal to the length of the known training sequence.
4. The method according to claim 3 , wherein the converting and combining processing further includes performing negate operation of the in phase components and the quadrature components of the respective sample points so as to obtain the negated in phase components and the negated quadrature components.
5. The method according to claim 4 , wherein the converting and combining processing further includes performing pre-defined combination operation of the in phase components, the negated in phase components, the quadrature components and the negated quadrature components of respective sample points, so as to obtain the corresponding output results of the respective sample points.
6. The method according to claim 5 , wherein the converting and combining processing further includes performing accumulation operation on the output results to which respective sample points in the same sampling sequence correspond to the sampling sequences, so as to obtain the matched filtered results corresponding to the sampling sequences.
7. The method according to claim 5 , wherein the output result to which the respective sample points correspond is one of a set of expected results.
8. The method according to claim 2 , wherein the wireless communication system is a Time Division-Synchronous Code Division Multiple Access (TD-SCDMA)-system, the numeric value of each unit of the known training sequence is one from the set {1, −1, j, −j}.
9. The method according to claim 7 , wherein the wireless communication system is a TD-SCDMA system, the set of expected results is one of the set {I+jQ, −I−jQ, −Q+jI, Q−jI}, wherein I is the in phase component, Q is the quadrature component, −I is the negated in phase component, −Q is the negated quadrature component.
10. The method according to claim 2 , wherein the wireless communication system is a Wideband Code Division Multiple Access (WCDMA) system, the numeric value of each unit of the known training sequence is one from the set {1+j, 1−j, 1+j, −1−j}.
11. The method according to claim 7 , wherein the wireless communication system is a Wideband Code Division Multiple Access (WCDMA) system, the set of expected results is one of the set {(I−Q)+j(I+Q), (I+Q)+j(−I+Q), (−I−Q)+j(I−Q), (−I+Q)+j(−I−Q)}, wherein I is the in phase component, Q is the quadrature component, −I is the negated in phase component, −Q is the negated quadrature component.
12. An apparatus for implementing matched filters in a wireless communication system, comprising:
an oversampling and extracting unit configured to oversample and extract a pre-processed received signal so as to obtain the in phase components and the quadrature components of respective sample points in a plurality of sampling sequences;
a conversion process unit configured to convert and combine the in phase components and the quadrature components of respective sample points in the same sampling sequence for the respective sampling sequence according to a pre-defined selection signal so as to obtain a plurality of corresponding matched filtered results;
a buffer configured to buffer the plurality of matched filtered results; and
a comparison unit configured to compare the plurality of matched filtered results that are buffered so as to determine an optimum matched sampling sequence, the matched filtered result to which the optimum matched sampling sequence corresponds has the greatest value.
13. The apparatus according to claim 12 , wherein the matched filters further comprise a pre-defined unit configured to define the pre-defined selection signal based on a selection signal of a known training sequence.
14. The apparatus according to claim 13 , wherein the respective sampling sequences are of the same length as the known training sequence.
15. The apparatus according to claim 14 , wherein the conversion process unit comprises a negating unit configured to perform negate operation of the in phase components and the quadrature components of the respective sample points so as to obtain the negated in phase components and the negated quadrature components.
16. The apparatus according to claim 15 , wherein the conversion process unit further comprises a signal combining unit configured to perform pre-defined combination operation of the in phase components, the negated in phase components, the quadrature components and the negated quadrature components of respective sample points, so as to obtain the corresponding output results of the respective sample points.
17. The apparatus according to claim 16 , wherein the conversion process unit further comprises an accumulating unit configured to perform accumulation operation on the output results to which respective sample points in the same sampling sequence correspond to the sampling sequences so as to obtain the matched filtered results corresponding to the sampling sequences.
18. The apparatus according to claim 16 , wherein the output result to which the respective sample points correspond is one of a set of expected results.
19. The apparatus according to claim 13 , wherein the wireless communication system is a Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) system, the numeric value of each unit of the known training sequence is one from the set {1, −1, j, −j}.
20. The apparatus according to claim 18 , wherein the wireless communication system is a TD-SCDMA system, the set of expected results is one of the set {I+j Q, −I−j Q, −Q+jI, Q−jI}, wherein I is the in phase component, Q is the quadrature component, −I is the negated in phase component, −Q is the negated quadrature component.
21. The apparatus according to claim 13 , wherein the wireless communication system is a Wideband Code Division Multiple Access (WCDMA) system, the numeric value of each unit of the known training sequence is one from the set {1+j, 1−j, 1+j, −1−j}.
22. The apparatus according to claim 18 , wherein the wireless communication system is a Wideband Code Division Multiple Access (WCDMA) system, the set of expected results is one of the set {(I−Q)+j(I+Q), (I+Q)+j(−I+Q), (−I−Q)+j(I−Q), (−I+Q)+j(−I−Q)}, wherein I is the in phase component, Q is the quadrature component, −I is the negated in phase component, −Q is the negated quadrature component.